Cancers are a leading cause of mortality worldwide. They may occur in a variety of organs, such as pancreas, ovaries, breasts, lung, colon, and rectum. Pancreatic cancers are the fourth most common cause of cancer deaths in the United States. Pancreatic cancers may occur in the exocrine or endocrine component of the pancreas. Exocrine cancers include (1) pancreatic adenocarcinoma, which is by far the most common type, (2) acinar cell carcinoma, which represents 5% of exocrine pancreatic cancers, (3) cystadenocarcinomas, which account for 1% of pancreatic cancers, and (4) other rare forms of cancers, such as pancreatoblastoma, adenosquamous carcinomas, signet ring cell carcinomas, hepatoid carcinomas, colloid carcinomas, undifferentiated carcinomas, and undifferentiated carcinomas with osteoclast-like giant cells.
Ovarian cancer accounts for about 3% of cancers among women, but it causes more deaths than any other cancer of the female reproductive system. Ovarian cancers include (1) epithelial cancers, such as epithelial ovarian carcinomas, (2) germ cell cancers, such as immature teratomas, and (3) stromal cancers, such as granulosa cell tumors.
Breast cancer is the second most common cancer among American women and the second leading cause of cancer death in women. Breast cancers can be classified based on the hormone receptors and HER2/neu status, such as (1) hormone receptor-positive cancers (where the cancer cells contain either estrogen receptors or progesterone receptors), (2) hormone receptor-negative cancers (where the cancer cells don't have either estrogen or progesterone receptors), (3) HER2/neu positive (wherein cancers that have excessive HER2/neu protein or extra copies of the HER2/neu gene), (4) HER2/neu negative cancers (where the cancers don't have excess HER2/neu), (5) triple-negative cancers (wherein the breast cancer cells have neither estrogen receptors, nor progesterone receptors, nor excessive HER2), and (6) triple-positive cancers (where the cancers are estrogen receptor-positive, progesterone receptor-positive, and have too much HER2).
Lung cancer accounts for more than a quarter of all cancer deaths and is by far the leading cause of cancer death among both men and women. The most common type of lung cancers is non-small cell lung cancers (NSCLC), which account for about 85% to 90% of lung cancers. NSCLC may be further classified into several subtypes, such as squamous cell (epidermoid) carcinoma, adenocarcinoma, large cell (undifferentiated) carcinoma, adenosquamous carcinoma, and sarcomatoid carcinoma. The second common type of lung cancer is small cell lung cancer (SCLC), which accounts for about 10% to 15% of all lung cancers.
Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the United States when both men and women are combined. Adenocarcinoma is the most common type of CRC, which accounts for more than 95% of colorectal cancers. Other less common types of CRC include Carcinoid tumors, gastrointestinal stromal tumors (GISTs), lymphomas, and sarcomas.
Gastric cancer is the third most common cause of cancer-related death in the world. It remains difficult to cure, primarily because most patients present with advanced disease. In the United States, gastric cancer is currently the 15th most common cancer. About 90-95% of gastric cancers are adenocarcinomas; other less common types include lymphoma (4%), GISTs, and carcinoid tumors (3%).
Traditional regimens of cancer management have been successful in the management of a selective group of circulating and solid cancers. However, many types of cancers are resistant to traditional approaches. In recent years, immunotherapy for cancers has been explored, particularly cancer vaccines and antibody therapies. One approach of cancer immunotherapy involves the administering an immunogen to generate an active systemic immune response towards a tumor-associated antigen (TAA) on the target cancer cell. While a large number of tumor-associated antigens have been identified and many of these antigens have been explored as viral-, bacterial-, protein-, peptide-, or DNA-based vaccines for the treatment or prevention of cancers, most clinical trials so far have failed to produce a therapeutic product. Therefore, there exists a need for immunogens that may be used in the treatment or prevention of cancers.
The present disclosure relates to immunogens derived from the tumor-associated antigens MUC1, mesothelin, and TERT, nucleic acid molecules encoding the immunogens, and compositions comprising such immunogens or nucleic acids.
The human mucin 1 (MUC1; also known as episialin, PEM, H23Ag, EMA, CA15-3, and MCA) is a polymorphic transmembrane glycoprotein expressed on the apical surfaces of simple and glandular epithelia. The MUC1 gene encodes a single polypeptide chain precursor that includes a signal peptide sequence. Immediately after translation the signal peptide sequence is removed and the remaining portion of the MUC1 precursor is further cleaved into two peptide fragments: the longer N-terminal subunit (MUC1-N or MUC1a) and the shorter C-terminal subunit (MUC1-C or MUC16). The mature MUC1 comprises a MUC1-N and a MUC1-C associated through stable hydrogen bonds. MUC1-N, which is an extracellular domain, contains 25 to 125 variable number tandem repeats (VNTR) of 20 amino acid residues. MUC1-C contains a short extracellular region (approximately 53 amino acids), a transmembrane domain (approximately 28 amino acid), and a cytoplasmic tail (approximately 72 amino acids). The cytoplasmic tail of MUC1 (MUC1-CT) contains highly conserved serine and tyrosine residues that are phosphorylated by growth factor receptors and intracellular kinases. Human MUC1 exists in multiple isoforms resulting from different types of MUC1 RNA alternative splicing. The amino acid sequence of full length human MUC1 isoform 1 protein precursor (isoform 1, Uniprot P15941-1) is provided in SEQ ID NO: 1 (“MUC1 Isoform 1 Reference Polypeptide”). At least 16 other isoforms of human MUC-1 have been reported so far (Uniprot P15941-2 through P15941-17), which include various insertions, deletions, or substitutions as compared to the sequence of isoform 1. These isoforms are known as isoform 2, 3, 4, 5, 6, Y, 8, 9, F, Y-LSP, S2, M6, ZD, T10, E2, and J13 (Uniprot P15941-2 through P15941-17, respectively). The full length human MUC1 isoform 1 precursor protein consists of 1255 amino acids, which includes a signal peptide sequence at amino acids 1-23. The MUC1-N and MUC1-C domains of the mature MUC1 protein consist of amino acids 24-1097 and 1098-1255, respectively.
Mesothelin (also known as MSLN) is a membrane-bound glycoprotein present on the surface of cells lining the pleura, peritoneum and pericardium, and is overexpressed in several human tumors, including mesothelioma, ovarian, and pancreatic adenocarcinoma. The Mesothelin gene encodes a 71-kilodalton (kDa) precursor protein that is processed to a 40-kDa Mesothelin protein and a secreted megakaryocyte potentiating factor (MPF) protein (Chang, et al, Proc Natl Acad Sci USA (1996) 93:136-40). Alternative splicing of MSLN gene results in at least four mesothelin isoforms. The amino acid sequences of isoform 1 (Uniprot Q13421-1), isoform 2 (Uniprot Q13421-3), isoform 3 (Uniprot Q13421-2), and isoform 4 (Uniprot Q13421-4) are available at Uniprot. The amino acid sequence of full length human MSLN isoform 2 precursor protein (Uniprot identifier Q13421-3), which consists of 622 amino acids, is provided in SEQ ID NO:2 (“Mesothelin Precursor Isoform 2 Reference Polypeptide”). The cytoplasmic portion of MSLN comprises amino acid residues 37 to 597 of SEQ ID NO:2 Isoform 2 is the major form of MSLN. Isoform 1, which consists of 630 amino acids, differs from isoform 2 by having an insertion of 8 amino acids (PQAPRRPL) at position 409 of the isoform 2 sequence. Isoform 3 has an alternative C terminus (at positions 593-622 of isoform 2) while isoform 4 has a deletion of amino acid 44, as compared with isoform 2. Isoform 2 is initially translated as a 622-amino acid precursor, which comprises a signal peptide sequence (amino acids 1-36) at the N-terminus and a GPI-anchor sequence at the C-terminus. The signal peptide sequence and the GPI-anchor sequence may be cleaved off in the mature mesothelin.
Telomerase reverse transcriptase (or TERT) is the catalytic component of the telomerase, which is a ribonucleoprotein polymerase responsible for maintaining telomere ends by addition of the telomere repeat TTAGGG. In addition to TERT, telomerase also includes an RNA component which serves as a template for the telomere repeat. Human TERT gene encodes an 1132 amino acid protein. Several isoforms of human TERT exist, which result from alternative splicing. The amino acid sequences of isoform 1, isoform 2, isoform 3, and isoform 4 are available at Uniprot (Uniprot identifiers 014746-1, 014746-2, 014746-3, and 014746-4, respectively). The amino acid sequence of human full length TERT isoform 1 protein (isoform 1, Genbank AAD30037, Uniprot 014746-1) is also provided herein in SEQ ID NO:3 (“TERT Isoform 1 Reference Polypeptide”). As compared with TERT isoform 1 (014746-1), isoform 2 (014746-2) has replacement of amino acids 764-807 (STLTDLQPYM (SEQ ID NO:622) . . . LNEASSGLFD (SEQ ID NO:623)→LRPVPGDPAG (SEQ ID NO:624) . . . AGRAAPAFGG (SEQ ID NO:625)) and deletion of C-terminal amino acids 808-1132), isoform 3 (014746-3) has deletion of amino acids 885-947, and isoform 4 (014746-4) has deletions of amino acids 711-722 and 808-1132, and replacement of amino acids 764-807 (STLTDLQPYM (SEQ ID NO:626) . . . LNEASSGLFD (SEQ ID NO:627)→LRPVPGDPAG (SEQ ID NO:628) . . . AGRAAPAFGG 9SEQ ID NO:629)).